Tick-borne infections are found worldwide. In the upper Midwest, this group of diseases consists primarily of tularemia,
borreliosis (Lyme disease), ehrlichiosis and anaplasmosis. Tularemia (Francisella tularensis) and borreliosis (Borrelia
burgdorferi) have been covered in prior publications; therefore, this discussion will focus on ehrlichiosis and anaplasmosis.
These diseases are passed from ticks to wild and domesticated animal reservoir hosts. Humans are infected when bitten by ticks carrying the pathogenic bacteria.

Borreliosis (Lyme disease) is the most commonly reported vector-borne (insect-transmitted) disease in the U.S. In this country, it is found primarily in the Northeast, upper Midwest and northern California. Boreliosis is caused by a spiral bacterium, Borrelia burgdorferi, that is found in a variety of reservoir hosts (birds, small and medium-sized mammals). Humans are infected by a tick bite.